docs: def add_timeline_callback(self, timeline_events, callback):
          """Register a callback for a specific timeline event."""
          if not timeline_events:
              return False
  
          if not isinstance(timeline_events, (tuple, list)):
              timeline_events = [timeline_events]
  
          for timeline_event in timeline_events:
              if not isinstance(timeline_event, dict):
                  raise AbodeException((ERROR.EVENT_CODE_MISSING))
  
              event_code = timeline_event.get('event_code')
  
              if not event_code:
                  raise AbodeException((ERROR.EVENT_CODE_MISSING))
  
              _LOGGER.debug("Subscribing to timeline event: %s", timeline_event)
  
              self._timeline_callbacks[event_code].append((callback))
  
          return True